1. Field of the Invention
The present invention relates to a system and method of watermarking.
2. Description of the Prior Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Digital media has the inherent feature that perfect duplicates can be made of it; this is useful when generating legitimate copies of the media for download or inclusion on a disk, but is obviously problematic when people generate and distribute unauthorised copies in so-called ‘piracy’.
There are numerous ways to combat piracy, some of which can place an undue burden on legitimate end-users of the media. However the inclusion of identification data that corresponds to specific instances of the digital media can be useful, in particular where the specific instance of the digital media can in turn be traced back to an individual.
The accountability of the individual has a chilling effect on the creation of unauthorised copies by those individuals, thereby reducing supply. In addition, where the media is validated by a secure online service, as is possible with video games, then knowing which specific instances of the digital media have been pirated can allow for unauthorised copies and their users to be identified by the secure online service. Again this can have a chilling effect, this time on demand for the unauthorised copies.
In pre-recorded media such as films, the identification data has taken the form of watermarks. Often these watermarks are concealed within the video image using steganography. Pirates have attempted to undermine such watermarking by a variety of techniques aimed at scrambling identification of the specific instance of the digital media, and in response watermarking techniques have become increasingly sophisticated and robust. However these robust techniques are generally based on having a predefined sequence of images to work with.
Meanwhile in videogames, traditionally the identification data is part of the program code and is validated by a secure online service, and hence there has been little need for visible watermarking to identify the source instance of a pirate copy.
However with the advent of social media and the prevalence of video capture of videogames on services such as YouTube® and Twitch®, the need to identify videogames using only the resulting video image, without access to the program code, has grown. This is particularly acute where review copies of games are distributed under conditions of confidence before general release of a game, but then footage of the game is leaked to the public in breach of that confidence. Again it will be desirable to bring individuals to account, or in the case of piracy to trace and/or disable the corresponding instance of the videogame being shown.
However it will be appreciated that in many videogames the generated imagery being shown is entirely dependent on the user's gameplay, making the inclusion of discrete and robust watermarks of the kind used in conventional pre-recorded media much more difficult.
The present invention aims to alleviate or mitigate this problem.